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Unread 05-24-2021, 03:18 PM   #2
Veteran DIYer- Schluterville Graduate

STAR Senior Contributor

Join Date: Jul 2004
Location: Nashua, NH
Posts: 14,511
You can tile over Ditra immediately after installation. If you're not going to do that, you should wait at least overnight and you'll find you may want to use something to spread your weight out like a small square of plywood while kneeling on it the next day. Before you grout the tile, you'll want to wait at least overnight, and a day or two is probably better...check to see if the grout has any stipulations on it...some may want more time. Before you apply any significant loads (setting your toilet, installing the vanity), you'll want to wait at least a few days, and a week wouldn't be bad.

There are at least four classes of things that can be used as modifiers. Many of them are stable while still wet. Latex, the original and still used with some, needs to dry to be come stable. The cement cures without drying, but if the stuff around it isn't stable, the curing cement can be fractured, preventing it from keeping a good bond.

The industry spec sheets don't make it evident what type of modifier is used in the US. Schluter knows an unmodified works on top of Ditra...they do not know if the modifier will. In Europe, the DIN specs do differentiate those features, so it's easy to list specs, and not have to test all brands and models like they'd have to do in the USA, especially if they ever changed the configuration, so they list ones they know will work.

It is critical to get the fleece bonded to the plywood, and that takes a modified. It is not critical on top of the sheet since thinset does NOT bond to the sheet, only to the tile. As a result, there's very little stress on the bond...the towers of thinset transmit vertical forces to the floor through the mat that is bonded to the floor, but with the grid, the whole floor acts more like a floating one than one that is bonded to it.
Jim DeBruycker
Not a pro, multiple Schluter Workshops (Schluterville and 2013 and 2014 at Schluter Headquarters), Mapei Training 2014, Laticrete Workshop 2014, Custom Building Products Workshop 2015, and Longtime Forum Participant.
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